Since the first beta for Firefox released, the developers have received tremendous response from user feedback are and they have created new feedback tools to interpret all the fantastic feedback given by the users.
From the Firefox Team:
We’ve actually gotten so much great feedback from users that we’ve had to create new tools to help us interpret it all. So keep on letting us know what you like about the new betas, and what isn’t working well for you, and we’ll keep on working with you to make sure that Firefox 4 is moar awesome.
Over the next two betas, new developer tools will be introduced and there will be a feature freeze.
To install it in Ubuntu add Mozilla daily ppa to your software sources:
The packages are not ready yet, but soon they will be there.
A multi-touch preview for windows: